Materials Literature
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Both the Young`s modulus sound velocity (V E ) and the internal friction (Q -1 ) have been measured for a polycrystalline sample of LiMn 2 O 4 in the temperature range between 35 and 350 K, using a vibrating-reed technique. The resonance frequency (f r ) employed for the measurement ranged from 0.81 kHz to 2.69 kHz at…
Interaction between two partial 90\ifmmode^\circ\else\textdegree\fi{} edge dislocations is studied with atomic-scale simulations using the effective-medium tight-binding method. A large separation between the two dislocations (up to 30 \AA{}), comparable to experimental values, is achieved with a solution of the tight…
A theory is presented for core hole polarization probed by spin polarization and magnetic dichroism in resonant photoemission. The resonant photoemission is considered as a two-step process, starting with an excitation from a core level to the valence shell, after which the core hole decays into two shallower core hol…
Characteristics of Schottky barriers formed on homoepitaxial diamond film have been studied. Current–voltage characteristics of Al contacts on both the as-grown film and the oxidized film show rectification. On the other hand, ohmic property is observed on Au/as-grown film while Au/oxidized film shows rectification. T…
The entropic depletion force in colloids arises when large particles are placed in a solution of smaller ones and sterically constrained to avoid them. We calculate the interaction between two hard spheres (of radius $R$) in a semidilute solution of hard rods of length $L$ and diameter $D$ ($D\ensuremath{\ll}L\ensurem…
A series of mixtures composed of a symmetric $A\ensuremath{-}B$ diblock copolymer and a symmetric blend of $A$ and $B$ homopolymers was investigated by small-angle neutron scattering. Mean-field theory predicts that a line of lamellar-disorder transitions with wave-vector instability ${q}^{*}>0$ will meet a line of…
This work investigates the temperature dependence of GaAs/AlAs thin-film structures. Based on an ac calorimetric method, the thermal diffusivity of a 700 Å/700 Å GaAs/AlAs periodic structure is measured from 190 to 450 K. Thermal conductivity of the structure is derived from the experiment. The results demonstrate tha…
The magnetic transitions in ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}\mathrm{Mn}{\mathrm{O}}_{3}$ ($x=0.25, 0.50$) were studied by synchrotron x-ray and neutron powder diffraction. For $x=0.25$ the large $\ensuremath{\Delta}V=0.13%$ at ${T}_{C}$ is due to the simultaneous insulator-to-metal transition. For $x…
We report measurements of the de Haas-van Alphen (dHvA) effect in the quasi-two-dimensional organic metal κ-(BEDT-TTF) 2 Cu(NCS) 2 by means of a capacitive torquemeter. The experiments were carried out in magnetic fields up to 29.5 T, at temperatures down to 0.4 K and for tilt angles θ between -35° and 80°. In the ang…
It is shown that the guided-mode resonance effects associated with waveguide gratings can be used to realize transmission bandpass filters. The key idea is the integration of the resonant waveguide gratings into a dielectric multilayer structure that efficiently reflects the off-resonance spectral components while pas…
An array of polymer grid triodes connected by a common grid functions as a “plastic retina,” providing local contrast gain control for image enhancement. This simple device, made from layers of conducting polymers, functions as an active resistive network that performs center-surround filtering. The polymer grid triod…
A theory based upon normal mode analysis (NMA) is used to calculate the self-diffusion constant, D, in the unit density Lennard-Jones liquid. The theory, which uses no adjustable parameters, is in good agreement with computer simulation over the reduced temperature range 20≥T≥0.42. Thus NMA appears applicable to syste…
The characteristics of the solid/liquid transition for a modified Simple Point Charge model of water have been determined using free energy calculations supported by nonequilibrium Molecular Dynamics (NEMD) simulations. We have considered the behavior of liquid water and of a variety of ice phases. Unlike real water,…
The specific interactions between sulphonic acid protonated polyaniline (PANI) and solvents are here studied both by the semiempirical AM1 method and experimentally. Phenolic solvents are shown to have a relatively large interaction with the sulphonate anions of the counterions and with the amines in PANI. In addition…
We report on a novel approach to the Deam-Edwards model (1976) for interacting polymeric networks without using replicas. Our approach utilizes the fact that a network modelled from a single non-interacting Gaussian chain of macroscopic size can be solved exactly, even for randomly distributed crosslinking junctions.…
We consider the statistics of generalized Gaussian structures (GGS) exposed to a random external field. A GGS comprises N monomers connected to each other by harmonic potentials. When the spectral dimension d, of a GGS exceeds the value of two its radius of gyration R becomes independent of its mass N. The cross-over…
We have carried out an ab-initio study of $α$-Sn (111), with the aim of predicting and understanding its structure, reconstructions, and electronic states. We consider a variety of structural possibilities, and optimize them by moving atoms according to Hellmann-Feynman forces. Our results indicate that the unreconstr…
This study used a two-dimensional finite element method to investigate the preferred design for a cast circumferential clasp. Finite element models of the clasp arm with the constant flexibility were constructed, the stress was calculated, and the effects of taper and cross-sectional shape on stress were evaluated. Th…
Theories of toughness of materials depend on an understanding of the characteristic instabilities of the crack tip, and their possible interactions. In this paper we examine the effect of dislocation emission on subsequent cleavage of a crack and on further dislocation emission. The work is an extension of the previou…
Abstract The light transmittance of the gels of poly(vinyl alcohol) (PVA)/phenol/water solutions was examined for the entire range of phenol/water content. Excellent transparency was found for the gels with phenol contents of 70–95 vol %. In full consideration of the results for the transparency and melting temperatur…